Communication service unit and connection sequence executing method

ABSTRACT

Communication is performed without paying attention to the fact that the communication is executed between multimedia terminals having communication procedures differing from each other.  
     A terminal  2  starts a communication procedure that is necessary to establish a communication path to a communication service unit  1 , in order to execute communication with a multimedia terminal  3 ; when a communication protocol conversion unit  7  receives communication start request from the terminal  2 , the communication service unit executes identification process of a calling terminal based on the identification number, which exists in communication start request, for determining the multimedia terminal  2 , and inquires a terminal information managing unit  9  of the calling terminal. The terminal information managing unit  9  retrieves terminal information related to the calling terminal based on a terminal information request, and informs of the retrieved terminal information to the communication protocol conversion unit  7 . The communication protocol conversion unit  7  informs of the communication start request to the terminal  3  when the transmitting the terminal information of the terminal  2  is obtained, and continues a relay process in communication procedure, which is necessary for following establishment of a communication path.

TECHNICAL FIELD

The present invention is related to a communication service unit and aconnection sequence operating method for packet-multiplexing encodedmedia information such as video, audio or data, and transmitting themedia information.

BACKGROUND ART

Various standards for multiplex-transmitting information of eachmultimedia have been established, with respect to multimedia terminalsfor realizing services such as a videophone by transmitting mediainformation such as video, audio or data.

With respect to multimedia terminals for realizing TV phone serviceprovided by the W-CDMA third generation mobile phones, for example, theITU-T (International Telecommunication Union-TelecommunicationStandardization Sector) Recommendation, H.324 (Terminal for low bit-ratemultimedia communication) is applied as one of the standards formultiplex-transmitting multimedia information. In a multimedia terminalin conformity with the international recommendation, the ITU-TRecommendation, H.324, the international recommendation, the ITU-TRecommendation, H.245 is applied as the AV communication controlprotocol that exchanges various setting for transmitting mediainformation and determine, meanwhile the international recommendation,the ITU-T Recommendation, H.223 (Multiplexing protocol for low bit ratemultimedia communication), is applied as a multimedia multiplexingsystem.

Moreover, in a multimedia terminal for realizing TV phone service usedin internet communication, for example, the IETF (Internet EngineeringTask Force) Standard, SIP (Session Initiation Protocol) is applied asone of the standards for multiplex-transmitting multimedia information.In a multimedia terminal in conformity with the IETF Standard, SIP, theIETF Standard, RTP (Real time Transport Protocol)/RTCP (Real timeTransport Control Protocol) is applied as a multimedia-multiplex system.

In communication among multimedia terminals, it is necessary not only toestablish a communication path for transmitting information, but also toestablish an encoding method for media information or a transmissionmethod for encoded media information, with respect to media informationsuch as video or audio, etc. that is actually transmitted and receivedamong the terminals. In the ITU-T Recommendation, H.324, multimediacommunication among multimedia terminals is established through twosteps including a communication procedure for establishing acommunication path, referred to as “Call control procedure”, and acommunication procedure for establishing the encoding method for mediainformation of video or audio, etc. or the transmission method for theencoded media information after communication such as called “AV mediacontrol sequence has been established”. On the other hand, in the IETFStandard, SIP, multimedia communication among multimedia terminals isestablished by a communication procedure that concurrently establishes acommunication path and an encoding method of media information such asvideo and audio or a transmission method for the encoded mediainformation. That is, with respect to communication information relatedto video and audio, for example, encode capability of media, in themultimedia terminal in conformity with the ITU-T Recommendation, H.324,information transmission and determination are performed in the mediacontrol procedure after having established the communication path, andin the multimedia terminal in conformity with the IETF Standard, SIP,information transmission and determination are performed in thecall-control and media-control procedures associated with theestablishment of communication paths.

Therefore, there causes a problem in that notifying timings of terminalinformation related to media information are different, when mutualcommunication is realized among the multimedia terminals in conformitywith the ITU-T Recommendation, H.324 and the multimedia terminal inconformity with the IETF Standard, SIP, which have differentcommunication procedures. For example, there is a problem in that themultimedia terminal in conformity with the ITU-T Recommendation, H.324can not inform the multimedia terminal in conformity with the IETFStandard, SIP, when they try to mutually communicate, because theterminal information related to media information of a calling terminalrequesting communication start is not included in the communicationprocedure of the terminals in conformity with the ITU-T Recommendation,H.324 at the time of communication start.

Coping with the above problems, in Japanese Laid-Open Open PatentPublications 1998-334007 and 2000-285043, it is described, as an emailtype facsimile device, how to relay between the different communicationprocedures in which information is transmitted through an IP network andthrough a circuit exchange network. Even in communication of facsimiledevices, it is necessary to inform each other of terminal informationsuch as receivable data type or video quality selection betweentransmitting facsimile devices and receiving facsimile devices, andtherefore the solutions to the problems are now disclosed.

In particular, the prior art described in Japanese Laid-Open Open PatentPublications 1998-334007 includes a transmitting facsimile type emaildevice, a facsimile type email device as a relay unit, a server, and areceiving facsimile device. Their terminal information such as telephonenumber of the facsimile device, mail address, receivable data type orvideo quality selection is managed in the server. In this situation, itis pointed out that the information is automatically registered in adatabase of the server, if an operator inputs information itemscorresponding to the terminal information and transmits the inputinformation by predetermined operation. Then, the transmitting facsimiledevice can obtain the terminal information in the database by inquiringthe terminal information on the receiving facsimile device whenfacsimile transmitting, select a most suitable transmitting method, andtransmit the facsimile information.

Moreover, the prior art described in Japanese Laid-Open Open PatentPublications 2000-285043 includes, in an environment composed of pluralIP networks, a DNS (domain name system) server and a means for inquiringanother server of terminal information to obtain the information if theterminal information is not stored in the database of the server.Therefore, even if the terminal information related to the receivingfacsimile device has not been stored directly, the terminal informationmay possibly be obtained, for example, by inquiring a server in the IPnetwork in which the terminal is included, and facsimile information canbe transmitted in a wider-area network environment. At this moment, byautomatically registering the terminal information obtained from anotherserver into its own server, the terminal information of the receivingfacsimile device can be obtained swiftly from the next time onward.

As described above, in a multimedia terminal in conformity with theITU-T Recommendation, H.324, two steps of procedures are executed, inwhich a transmission path (call control procedure) and mediacommunication (AV media control procedure) are established. On the otherhand, in a multimedia terminal in conformity with the IETF Standard,SIP, the call control procedure and the AV media control procedure areexecuted at the same time. Therefore, when both the terminals aremutually connected, there may be a problem in that necessary informationis insufficiently exchanged due to the difference of the communicationprocedures.

Moreover, in the method for obtaining the terminal information relatedto the receiving facsimile devices disclosed in above Japanese Laid-OpenOpen Patent Publications 1998-334007 or 2000-285043, necessaryinformation items must be inputted by an operator in advance. In otherwords, the specification related to the receiving facsimile devices mustbe obtained. Moreover, if there is information that can not be usuallyrecognized because the information is only exchanged by communicationprocedures between the devices, a problem occurs in that the presentmethod can not be applied.

In the multimedia terminals such as those in conformity with the ITU-TRecommendation, H.324 or in conformity with the IETF Standard, SIP, inaddition to information items selected by a user through an operationpanel, etc., there exists terminal information that is determined byspecific device specifications such as, for example, parameters relatedto a media encoding method or parameters related to amultiplex-transmission system for encoded media information, exchangedonly by communication procedures among the terminals, and that can notbe usually recognized.

Therefore, the present invention has been made accordingly in order toprovide a communication service unit and an operation method forperforming connection sequence, wherein information including theterminal information that the user can not obtain can be easily andautomatically registered into the database, and, even in the case ofcommunication between the multimedia terminals having communicationprocedures differing from each other, the user can start mutualcommunication without paying attention to the fact that those terminalshave communication procedures differing from each other.

DISCLOSURE OF THE INVENTION

In order to solve the above-described problems, in the presentinvention, it is basically addressed that, when a communication protocolis converted and relayed at the time of transmitting information fromone of terminals to another terminal, having different protocol systems,the calling terminal is identified, the terminal information related tothe calling terminal is retrieved from the terminal information storedin advance, and the connection sequence with the called terminal iscarried out using the retrieved terminal information. In particular,when the terminal information related to the calling terminal does notexist, communication connection to the called terminal is not executed,but a quasi communication procedure for obtaining the terminalinformation of the calling terminal is executed, so that the terminalinformation of the calling terminal is obtained and registered.

According to this invention as explained above, because thecommunication service unit is situated among communication terminalshaving communication protocol systems differing from each other; when acommunication protocol is converted and relayed while information istransmitted from one of terminals to another, the terminal informationrelated to a calling terminal is retrieved from the prerecorded terminalinformation by identifying the calling terminal; and a connectionsequence with the called terminal is basically executed by using theretrieved terminal information, if the communication is executed betweenthe multimedia terminals having communication procedures differing fromeach other, these terminals can mutually start communication withoutrecognizing that those terminals have communication procedures differingfrom each other.

In particular, because, when the terminal information related to thecalling terminal does not exist, communication connection to the calledterminal is not executed, but quasi communication procedure forobtaining the terminal information of the calling terminal is executed,so that the terminal information of the calling terminal is obtained andregistered, the terminal information can be automatically obtained evenif the terminal information related to the calling terminal does notexist.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a block diagram illustrating a communication service unitaccording to Embodiment 1 of the invention;

FIG. 2 is a diagram illustrating an example of sequence at thecommunication start according to Embodiment 1;

FIG. 3 is a diagram illustrating an example of sequence at thecommunication start according to Embodiment 2;

FIG. 4 is a block diagram illustrating a communication service unitaccording to Embodiment 4 of the invention;

FIG. 5 is a diagram illustrating an example of terminal informationrelated to a calling terminal whose information is retrieved in thecommunication service unit 1 in Embodiment 5;

FIG. 6 is a diagram illustrating an example of conversion of encodedmedia information such as video or audio in Embodiment 6; and

FIG. 7 is a diagram illustrating an example of conversion of encodedmedia information such as video or audio in Embodiment 7.

BEST MODE FOR CARRYING OUT THE INVENTION Embodiment 1

FIG. 1 is a block diagram illustrating a communication service unitaccording to Embodiment 1 of the invention.

In FIG. 1, “1” is an overall view of the communication service unit forrealizing mutual communication among multimedia terminals havingcommunication procedures differing from each other, “2” is a multimediaterminal for transmitting transmission stream to which media informationsuch as video or audio is encoded and multiplexed, or, to the contrary,for receiving the transmission stream, and decoding encoded mediainformation such as video or audio to obtain separated video or audiofrom the transmission stream, and “3” is a multimedia terminal havingcommunication procedure differing from communication procedure of themultimedia terminal 2. Moreover, “4” is a device control unit forcontrolling the communication service unit 1, “5” is a network interfaceunit for transmitting and receiving the transmission stream through themultimedia terminal 2 and a network A, and “6” is a network interfaceunit for transmitting and receiving the transmission stream through themultimedia terminal 3 and a network B. The network interface units 5 and6 have functions for transmitting and receiving media information orcommunication control information such as video or audio, astransmission streams, according to the standard to which multimediaterminals that are the communication target of each network interface,conform. “7” is a communication protocol conversion unit for mutuallytranslating and relaying the communication control information from themultimedia terminals 2 and 3 through the network interface units 5 and6, “8” is a media conversion unit for mutually translating and relayingencoded media information such as video or audio, from the multimediaterminals 2 and 3 through the network interfaces unit 5 and 6, and “9”is a terminal information managing unit for managing terminalinformation related to the multimedia terminals, which are a target ofmutual communication.

Next, operations in Embodiment 1 are explained. In this case, as one ofexamples, operations in a mutual communication from the multimediaterminal 2 to the multimedia terminal 3 through the communicationservice unit 1 are explained.

FIG. 2 is a diagram illustrating an example of sequence at the time ofcommunication start according to Embodiment 1.

The multimedia terminal 2, in order to execute mutual communication withthe multimedia terminal 3, starts a communication procedure that isnecessary to establish a communication path to the communication serviceunit 1. The communication service unit 1 executes a communicationprocedure, concerning communication start from the multimedia terminal2, in the communication protocol conversion unit 7 through the networkinterface unit 5 under the unitary control by the device control unit 4.Then, the communication protocol conversion unit 7 protocol-converts thecommunication message that is reported from the multimedia terminal 2,which is the calling terminal, and starts communication to themultimedia terminal 3 through the network interface unit 6. At thismoment, if the communication protocol conversion unit 7 receives acommunication massage 20, requesting communication start, which isreported from the multimedia terminal 2, which is the calling terminal,the unit executes calling terminal identification process 21 based onthe identification number for determining the multimedia terminal 2,which exists in the communication start request 20, that is, forexample, a transmitting phone number in the case of the multimediaterminal in conformity with the ITU-T Recommendation, H.324, or aterminal address, referred to as the SIP-URL in IP network, in the caseof multimedia terminal in conformity with the IETF Standard, SIP. Then,the conversion unit informs the terminal information managing unit 9 ofinquiry on the calling terminal in accordance with terminal informationrequest 22.

The terminal information managing unit 9 executes retrieving process 23for the terminal information related to the calling terminal inaccordance with the terminal information request 22. Then, the terminalinformation, which is the detected result, related to the callingterminal is reported by a terminal information reply 24. Thecommunication protocol conversion unit 7 executes determination process25 as to whether the protocol conversion process is continued, inaccordance with the terminal information reply 24. At this moment, ifthe calling terminal information of the multimedia terminal 2, which isthe calling terminal, has been obtained, a communication message 26relating to communication start request is reported to the multimediaterminal 3, and relay process of communication procedure, which isnecessary to following establishment of communication path, iscontinuously executed. Then, media control procedure, which is necessaryto multimedia transmission between the multimedia terminal 2 andmultimedia terminal 3, is executed.

At this moment, if the multimedia terminal 2 and multimedia terminal 3have communication procedures differing from each other, the quantityand contents of communication messages reported from both the multimediaterminals are different, and those do not always correspond one to one.In this case, the calling terminal information obtained by thecommunication protocol conversion unit 7 is applied, and thecommunication message is converted according to need.

Moreover, the database related to the terminal information, which isreferred in the retrieving process 23 of the terminal information by theterminal information managing unit 9 may be managed in the communicationservice unit 1, or may be unitarily managed to be inquired, by adedicated server outside the communication service unit 1.

Accordance to Embodiment 1 as described above, even if the terminalinformation, which is necessary for communication start procedure, isinsufficient, when mutual communication is executed between themultimedia terminal 2 and the multimedia terminal, 3 havingcommunication procedures differing from each other, an effect can beobtained, in which mutual communication can be realized, withoutrecognizing that the communication is executed between the multimediaterminal 2 and the multimedia terminal 3, having communicationprocedures differing from each other, by compensating the obtainedterminal information with the retrieved terminal information related tothe calling terminal in the communication service unit 1.

Embodiment 2

Because a block diagram of Embodiment 2 is identical to FIG. 1, which isthe block diagram of Embodiment 1, explanation of the configuration isomitted, and operations of Embodiment 2 are explained. Here, as anexample, operations in mutual communication from the multimedia terminal2 to the multimedia terminal 3 through the communication service unit 1are explained.

FIG. 3 is a diagram illustrating an example of sequence at thecommunication start according to Embodiment 3.

In the communication service unit 1, as described in Embodiment 1, whenthe communication massage 20 included in the communication start request20 is received from the multimedia terminal 2, terminal informationrelated to the multimedia terminal 2, which is a calling terminal, isinquired by the terminal information request 22 to the terminalinformation managing unit 9. The terminal information managing unit 9executes the retrieving process 23 of the terminal information relatedto the calling terminal according to the terminal information request22. Then, the terminal information related to the calling terminal isreported by a terminal information reply 30. At this moment, if theterminal information related to the calling terminal does not exist inthe database, a message that the terminal information can not beobtained is reported by the terminal information reply 30. Thecommunication protocol conversion unit 7 executes the determinationprocess 25 as to whether the protocol conversion process is continued bythe terminal information reply 30, and if the calling terminalinformation of the multimedia terminal 2 has not been obtained,communication to the multimedia terminal 3 is not executed and afollowing process progresses to acquire the terminal information fromthe multimedia terminal 2.

The communication protocol conversion unit 7 executes quasicommunication procedure, which is necessary for the multimedia terminal2 in establishing a communication path, by informing the multimediaterminal 2 of a communication message 31 of a communication start reply.After the establishment of the communication path, the multimediaterminal 2 starts a communication procedure, which is necessary formultimedia transmission. At this moment, if a media control message 32as to terminal capability notification reported from the multimediaterminal 2, is received, information related to multimedia transmissionof the multimedia terminal 2, which is a calling terminal is extractedfrom the terminal capability notification 32, and a process 33 isexecuted to obtain information related to the calling terminal. Next,the communication protocol conversion unit 7 informs the terminalinformation managing unit 9 of the information registration of thecalling terminal in accordance with terminal information registration34. The terminal information managing unit 9 executes a registrationprocess 36 of the terminal information related to the calling terminalin accordance with the terminal information registration 34. Meanwhile,quasi communication procedure, which is necessary for multimediatransmission of the multimedia terminal 2, is executed by informing themultimedia terminal 2 of a media control message 35 as to the terminalcapability notification.

At this moment, if the multimedia terminal 2 and multimedia terminal 3have communication procedures differing from each other, the quantityand contents of communication messages reported from both the multimediaterminals are different, and those does not always correspond one toone. In this case, the calling terminal information obtained by thecommunication protocol conversion unit 7 is applied, and thecommunication message is converted according to need. Moreover, everytime the terminal information related to the calling terminal isreported by other media control message that the multimedia terminal 3informs of, the terminal information registration process 36 of thecalling terminal may be executed. After that, the communication may oncebe terminated in accordance with the operator's decision as to themultimedia terminal 2, and then the communication to the multimediaterminal 3 may be started again. In this case, because the terminalinformation of calling terminal is registered in the database,multimedia communication between the multimedia terminal 2 and themultimedia terminal 3 is established based on the procedure illustratedin FIG. 1 in the communication service unit 1.

Moreover, the database related to terminal information, which theterminal information managing unit 9 refers in the retrieving process 23of terminal information, may be managed in the communication serviceunit 1, or may be unitarily managed to be inquired, by a dedicatedserver outside the communication service unit 1.

According to Embodiment 2 as described above, even if the terminalinformation related to the calling terminal, which is necessary for thecommunication procedure, is insufficient, when mutual communication isexecuted between the multimedia terminal 2 and the multimedia terminal 3having communication procedures differing from each other, an effect canbe exerted, in which, in the communication service unit 1, the terminalinformation can be automatically obtained from the calling terminalwithout inputting information through complicated procedures by theoperator.

Embodiment 3

Because a block diagram of Embodiment 3 is identical to FIG. 1, which isthe block diagram of Embodiment 1, explanation of the configuration isomitted, and operations of Embodiment 3 are explained. Here, as anexample, operations in mutual communication from the multimedia terminal2 to the multimedia terminal 3 through the communication service unit 1are explained.

When terminal information related to the calling terminal does not existin the database as described in FIG. 3, quasi multimedia communicationis established after having established a communication path between themultimedia terminal 2 and the communication service unit 1, andexchanged a series of communication messages or media control messages,which are necessary for establishment of the communication path andestablishment of media transmission, so as to obtain the terminalinformation related to the multimedia terminal 2, which is a callingterminal.

At this moment, in Embodiment 3, multimedia communication from thecommunication service unit 1 to the multimedia terminal 3 isestablished, while holding quasi multimedia communication, which hasbeen established between the multimedia terminal 2 and the communicationservice unit 1. In this case, after establishment of multimediacommunication by executing communication procedures for establishing thecommunication path and for establishing media transmission, multimediacommunication progresses to that between the multimedia terminal 2 andthe multimedia terminal 3 by relaying each of multimedia communicationbetween the multimedia terminal 2 and the communication service unit 1,and multimedia communication between the communication service unit 1and the multimedia terminal 3.

According to Embodiment 3 as described above, if the terminalinformation, which is necessary for the communication start procedure,is insufficient when mutual communication is executed between themultimedia terminal 2 and the multimedia terminal 3 having communicationprocedures differing from each other, an effect can be exerted, inwhich, in the communication service unit 1, the terminal information canbe automatically obtained from the calling terminal without inputtinginformation in accordance with complicated procedures by the operator,and the multimedia information can be automatically established in themultimedia terminal 3, which is a destination terminal.

Embodiment 4

FIG. 4 is a block diagram illustrating a communication service unitaccording to Embodiment 4, to which this invention is applied. Inaddition, the configuration of the communication service unit inEmbodiment 4 is, except for a guidance control unit 40, the same as theconfiguration of the communication service unit in Embodiment 1.

In FIG. 4, “40” is the guidance control unit that manages streamsencoded from media information such as video or audio; whencommunication start is requested from a multimedia terminal, althoughthe terminal information related to the multimedia terminal has not beenregistered in the database, the guidance control unit establishes, toobtain the terminal information, quasi multimedia communication betweenthe communication service unit 1 and the guidance control unit; and, atthis moment, the unit reports encoded media information equivalent toguidance video such as that for explaining communication status or anoperational procedure from the communication service unit 1 to thecorresponding multimedia terminal.

Next, the operations in Embodiment 4 are explained.

Here, as an example, operations in mutual communication from themultimedia terminal 2 to the multimedia terminal 3 through thecommunication service unit 1 are explained. When the terminalinformation related to the multimedia terminal 2, which is a callingterminal does not exist in the database as described in FIG. 3, quasimultimedia communication is established after having established acommunication path between the multimedia terminal 2 and thecommunication service unit 1, and exchanged a series of communicationmessage or media control message, which are necessary for establishmentof the communication path and establishment of media transmission, so asto obtain the terminal information related to the calling terminal.

At this moment, in Embodiment 4, guidance video for explaining status isreported from a guidance control unit 40 to the multimedia terminal 2,which is a calling terminal, while quasi multi media communication thathas been established between the multimedia terminal 2 and thecommunication service unit 1, is being executed. For example, in casesthat an operator of the multimedia terminal 2 needs to once terminatecommunication and restart the communication to the multimedia terminal3, guidance video is reported for explaining the status to the operatorof the multimedia terminal 2. Meanwhile, in cases, while the quasimultimedia communication established between the multimedia terminal 2and the communication service unit 1 is held, multimedia communicationfrom the communication service unit 1 to the multimedia terminal 3 isestablished, and the communication progresses to multimediacommunication between the multimedia terminal 2 and the multimediaterminal 3, guidance video for explaining the situation is reported tothe operator of the multimedia terminal 2 while the communication is inprogress toward the final communication state. Moreover, it goes withoutsaying that the guidance video may contain not only video but alsoaudio.

According to Embodiment 4 as described above, even if the terminalinformation, which is necessary for the communication procedure, isinsufficient when mutual communication is executed between themultimedia terminal 2 and the multimedia terminal 3 having communicationprocedures differing from each other, an effect can be exerted, inwhich, in the communication service unit 1, the terminal information canbe automatically obtained from the calling terminal without inputtinginformation in accordance with complicated procedures by the operator,and the operator can easily establish multimedia communication to thedestination terminal by informing the operator of the calling terminalof guidance video for explaining operational status.

Embodiment 5

Because a block diagram of Embodiment 5 is identical to FIG. 1, which isthe block diagram of Embodiment 1, explanation of the configuration isomitted, and operations of Embodiment 5 are explained.

FIG. 5 is a diagram illustrating an example of terminal informationrelated to the calling terminal retrieved in the communication serviceunit 1 in Embodiment 5.

In the database related to the terminal information referred by theterminal information managing unit 9 in retrieving process 23 of theterminal information, various information related to media controlmessages that are exchanged among terminals when the calling terminalcommunicates to other multimedia terminals. The terminal informationincludes; an identification number for specifying the calling terminal,for example, a transmitting phone number on circuit exchanging networkin the case of a multimedia terminal in conformity with the ITU-TRecommendation, H.324, or a terminal address referred to as the SIP-URLin the case of a multimedia terminal in conformity with the IETFStandard, SIP; a media encoding capability that can be applied to mediainformation such as video or audio that the terminal can transmit, forexample, a video encoding method or audio encoding method such as theMPEG-4 Visual or H.263, the AMR, and G.723.1; and unique information toeach media encoding method, for example, the DCI (decoder configurationinformation) as encoding information in the case of applying the MPEG-4Visual to the video encoding method.

When mutual communication from the multimedia terminal 2 to themultimedia terminal 3 is executed, an identification number is reportedas illustrated in FIG. 2, in which it serves for specifying the callingterminal in accordance with the communication start request 20 from themultimedia terminal 2. Therefore, if the terminal information related tothe calling terminal is registered in the database correlating theinformation to the identification number for specifying the callingterminal, the terminal can be easily retrieved by applying the reportedidentification number.

Moreover, similarly to Embodiments 1 to 4 described above, the databasein which the terminal information has been stored may be managed in thecommunication service unit 1, or may be unitarily managed to beinquired, by a dedicated server outside the communication service unit1. If the database is unitarily managed by a dedicated server outsidethe communication service unit 1, it is clear that the procedure, whichis the same method as that for inquiring and registering the terminalinformation between the communication protocol conversion unit 7 and theterminal information managing unit 9 in the communication service unit1, can be realized by inquiring and registering the terminal informationbetween the communication service unit 1 and the dedicated server. Then,because the terminal information related to the calling terminal is heldin the dedicated server, the system can easily be extended withoutmaking any particular arrangements, even when the number of thecommunication service unit 1 increases to plural.

According to Embodiment 5 as described above, if the terminalinformation, which is necessary for communication procedure, isinsufficient when mutual communication is executed between themultimedia terminal 2 and the multimedia terminal 3 having communicationprocedures differing from each other, an effect can be obtained, inwhich necessary information can be swiftly retrieved at thecommunication start with the multimedia terminal, by managing variousterminal information necessary for multimedia communication correlatingthe terminal information to the identification number for specifying thecalling terminal. Moreover, if the information related to the callingterminal is unitarily managed by the dedicated server outside thecommunication service unit 1, an effect can be obtained, in which thesystem can be easily extended even in the case of constructing thesystem with a plurality of communication service unit 1.

Embodiment 6

Because a block diagram of Embodiment 6 is identical to FIG. 1, which isthe block diagram of Embodiment 1, explanation of the configuration isomitted. Here, as an example, an operation in mutual communication fromthe multimedia terminal 2 to the multimedia terminal 3 through thecommunication service unit 1 is explained.

FIG. 6 is a diagram illustrating a conversion example of encoded mediainformation such as video or audio in Embodiment 6.

In FIG. 6, “50” and “51” are video media information and audio mediainformation reported from the multimedia terminal 2 to the communicationservice unit 1, and “52” is synchronizing information that has beenrecorded as prior information to the multimedia terminal 2 and isnecessary for the called terminal side for synchronously reproducing thevideo media information and the audio media information. “53” and “54”are video media information and audio media information that areappropriately converted by the media conversion unit 8 from the videomedia information 50 and the audio media information 51, and thenreported from the communication service unit 1 to the multimediaterminal 1.

Next, operations in Embodiment 6 are explained.

In Embodiment 6 of the invention, for example, it is assumed that thoughthe multimedia terminal 2 has a means for informing of the synchronizinginformation 52 in accordance with a communication procedure, themultimedia terminal 3 does not have a means for informing of informationcorresponding to the synchronizing information 52, but has differentprocedures such as a procedure to add time information to each ofpackets that transmit media information such as video or audio.

Here, for example, it is given that the value of the synchronizinginformation 52 registered in the terminal information of the multimediaterminal 2 is, for example, “T”, the receiving time of the video mediainformation 50 reported from the multimedia terminal 2 is “tv”, andsimilarly the receiving time of the audio media information 51 is “ta”.In the media conversion unit 9, the value of the synchronizinginformation 52 is applied to correct the receiving times of the videomedia information 50 and the audio media information 51 in thecommunication service unit 1, and then the corrected times are reflectedon time information “tv′” and “ta′” that are added to the video mediainformation 53 and the audio media information 54, which are reported tothe multimedia terminal 3. For example, regarding the time information“tv′” and “ta′”, that are given to the video media information 53, whenthe times received from the multimedia terminal 2 are applied directly,and conversion process given by “tv′”=“tv+α” is executed, the timeinformation “ta′”, which is given to the audio media information 54, isadded with only “T” minutes from the synchronizing information 52,resulting in “ta′”=“ta+α+T”. At this moment, regarding the timeinformation “tv′” and “ta′” that are given to the video mediainformation 53 and 54, respectively, the fixed offset value “α” may bedecided and be applied to their corrections, taking a process delay timein the communication service unit 1 into consideration.

According to Embodiment 6 as described above, when mutual communicationis executed between the multimedia terminal 2 and the multimediaterminal 3 having communication procedures differing from each other, aneffect can be obtained, in which relay process in which timesynchronizing is maintained among plural media information items withrespect to multimedia terminals without procedures to inform of thesynchronizing information, by holding, as the terminal information ofthe calling terminal, the synchronizing information for synchronouslyreproducing, at the receiving side, media information such as video oraudio, and by adjusting time information given to each media informationbased on the synchronizing information.

Embodiment 7

Because the block diagram of Embodiment 7 is identical to FIG. 1, whichis the block diagram of Embodiment 1, explanation of the configurationis omitted. In this case, as an example, operations in mutualcommunication from the multimedia terminal 2 to the multimedia terminal3 through the communication service unit 1 are explained.

FIG. 7 is a diagram illustrating an example of conversion of encodedmedia information such as video or audio in Embodiment 7.

In FIG. 7, “55” and “56” are video media information and audio mediainformation that are appropriately conversion-processed by the mediaconversion unit 8 with respect to the video media information 50 and theaudio media information 51, and reported from the communication serviceunit 1 to the multimedia terminal 3, and “57” and “58” are referencetime information to report the video media information “55” and theaudio media information “56” of reproducing timing.

Next, operations of Embodiment 7 are explained.

In Embodiment 7 of the invention, an example is assumed such that themultimedia terminal 2 has a means for informing of the synchronizinginformation 52 in accordance with its communication procedure, meanwhilethe multimedia terminal 3 does not have a means for informing ofinformation corresponding to the synchronizing information 52, but hasdifferent procedures such as that gives time information to each packetsin which media information such as video or audio is transmitted, andinforms of the media information, and also informs of time information,which is the time information reference of each media information.

Given that the value of the synchronizing information 52 registered inthe terminal information of the multimedia terminal 2 is, for example,“T”, the receiving time of the video media information 50 reported fromthe multimedia terminal 2 is “tv”, and the receiving time of the audiomedia information 51 is “ta”, the media conversion unit 9 applies thevalue of the synchronizing information 52 to correct in thecommunication service unit 1, receiving times of the video mediainformation 50 and the audio media information 51. At this moment, if aconversion process is executed to the time information “tv2′” and“ta2′”, which are given to the video media information 53 and the audiomedia information 54, in such a way that “tv2′”=“tv+α” and “ta2′”=“ta+α”in accordance with the times reported to the communication service unit1, the time information is reflected on the time information “tbv′” and“tba′”, which are time information references with respect to each mediainformation. For example, the time information “tba′”, which is thereference to the audio media information 56, is added with “T” minutesto the synchronizing information 52 resulting in “tba′”=“ta+β+T”, if thetimes received from the multimedia terminal 2 are directly applied tothe time information “tbv′”, which is the reference to the video mediainformation 55, and a conversion process given by “tbv′”=“tv+β” isexecuted. At this moment, with respect to the time information “tv2′”and “ta2′” that are given to the video media information 55 and 56 orwith respect to the time information “tbv′” and “tba′” that are thereference to each media information, the fixed offset value “α” and “β”may be decided and be applied to their correction taking a processingdelay time in the communication service unit 1 into consideration.

According to Embodiment 7 as described above, when mutual communicationis executed between the multimedia terminal 2 and the multimediaterminal 3 having communication procedures differing from each other, aneffect can be obtained, in which relay process in which timesynchronizing is matched among plural media information items withrespect to multimedia terminals without procedures to inform of thesynchronizing information, by holding, as the terminal information ofthe calling terminal, the synchronizing information for synchronouslyreproducing, at the receiving side, media information such as, video oraudio, and by adjusting time information that is the time informationreference given to each media information based on the synchronizinginformation.

1-10. (canceled)
 11. A communication service method, comprising:establishing a communication link between a first terminal supporting afirst communication protocol and a communication service unit configuredto convert a received first communication message, sent by the firstterminal and complying with the first communication protocol, to asecond communication message complying with a second communicationprotocol for transmitting the second communication message to a secondterminal supporting the second communication protocol; obtaining at thecommunication service unit terminal information related to the firstterminal from the first terminal through the communication link betweenthe first terminal and the communication service unit, the terminalinformation to be used for executing a sequence for connecting the firstterminal to the second terminal; and recording the terminal informationof the first terminal obtained through the communication link in adatabase accessible by the communication service unit.
 12. Acommunication service method according to claim 11, further comprising:establishing a communication link between the communication service unitand the second terminal after the recording.
 13. A communication servicemethod according to claim 11, further comprising: transmitting guidancefor explaining communication status or operation methods from thecommunication service unit to the first terminal.
 14. A communicationservice method according to claim 11, further comprising: saidcommunication service unit correlating the obtained terminal informationof the first terminal with an identification number of the firstterminal allocated to the first terminal to be identified on a network;and the recording comprising recording the terminal information of thefirst terminal correlated with the identification number of the firstterminal.
 15. A communication service method according to claim 11,wherein the establishing comprising: receiving at the communicationservice unit terminal information including at least one of anencoding-method classification for media that is to be applied during amultimedia communication, unique information for each encoding-methodclassification for media, and a moving parameter related to encoding.16. A communication service method according to claim 11, wherein theestablishing comprising: receiving at the communication service unitterminal information including synchronizing timing information to beused to synchronize different kinds of media information under the firstcommunication protocol; the communication service method furthercomprising: allocating timing information to be used under the secondcommunication protocol to media information to be relayed by thecommunication service unit from the first terminal to the secondterminal; adjusting the timing information based on the synchronizingtiming information; and relaying the adjusted timing information and themedia information to the second terminal via the communication serviceunit.
 17. A communication service method according to claim 11, whereinthe establishing comprising: receiving at the communication service unitterminal information including synchronizing timing information to beused to synchronize different kinds of media information under the firstcommunication protocol; the communication service method furthercomprising: allocating time information to be used under the secondcommunication protocol to media information to be relayed by thecommunication service unit from the first terminal to the secondterminal; adjusting, based on the synchronizing timing information,reference information serving as a reference of the time informationunder the second communication protocol; and relaying the adjustedreference information, the time information and the media information tothe second terminal via the communication service unit.
 18. Acommunication service method according to claim 11, further comprising:managing the data base in the recording in an external server.
 19. Acommunication service method, comprising: establishing a communicationlink between a first terminal supporting a first communication protocoland a communication service unit configured to convert a received firstcommunication message, sent by the first terminal and complying with thefirst communication protocol, to a second communication messagecomplying with a second communication protocol for transmitting thesecond communication message to a second terminal supporting the secondcommunication protocol; obtaining at the communication service unitterminal information related to the first terminal the terminalinformation including at least one of an encoding-method classificationfor media of the first terminal to be applied during a multimediacommunication and unique information for encoding-method classificationfor media of the first terminal from the first terminal through thecommunication between the first terminal and the communication serviceunit; and converting at the communication service unit the receivedfirst communication message, sent by the first terminal and complyingwith the first communication protocol to the second communicationmessage complying with the second communication protocol based on theobtained terminal information related to the first terminal.
 20. Acommunication service method according to claim 19, further comprising:recording the obtained terminal information of the first terminal in adatabase accessibly by the communication service unit.